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8. To activate the biological
indicator, place it in an Attest™
Biological Indicator Activator.
Close and squeeze the activator
to close the 1492V BI cap and
crush the media ampoule. Then
remove the BI and flick it (see
pictures at right). Visually verify
that media has flowed into the
growth chamber at the bottom of
the vial. If the media hasn't filled
the growth chamber, hold the BI
by the cap and flick it until media
fills the growth chamber. Place
the activated 1492V BI:
-
in any well of a 490 or 490H
Auto-reader having software
version 4.0.0 or greater
or
-
in an incubation well of a
490 Auto-reader having
software version less than
4.0.0 which is color-coded
brown (i.e., configured to
incubate 1492V BIs)
or
-
in any well of a 490M
Auto-reader
and wait for the result. See the
Auto-reader Operator's Manual
for further information related
to its use.
9. Each day that a processed
1492V BI is incubated, activate
and incubate at least one
non-processed 1492V BI to use as a positive control. Follow the activation
instructions provided in Step 8 above. Write a "C" (for "control") and the date
on the BI label. The positive control should be from the same lot code as the
processed biological indicator. The positive control BI helps confirm:
•
correct incubation temperatures are met,
•
viability of spores has not been altered due to improper storage
temperature, humidity or proximity to chemicals,
•
capability of media to promote rapid growth, and
•
proper functioning of the Auto-reader.
10. Incubation and Reading:
Incubate the positive control and steam processed 1492V BIs in a
490 Auto-reader, a 490H Auto-reader having software version 4.0.0 or greater,
or a 490M Auto-reader. See the applicable Auto-reader Operator's Manual for
the proper use of this equipment. The Auto-reader will indicate a positive result
as soon as it is obtained. The final negative 1492V BI reading is made at:
-
24 minutes in 490 or 490H Auto-readers having software version
4.0.0 or greater and in 490M Auto-readers
-
1 hour in 490 Auto-readers having software version less than 4.0.0.
After the results are displayed and recorded, the 1492V BIs may be discarded.
Interpretation of Results
Fluorescent Results
The positive control (unprocessed) 1492V BI must provide a positive fluorescent
result (+ on the Auto-reader display). Processed 1492V BI results are not valid until
the positive control reads fluorescent positive. If the positive control reads negative
(- on the display), check the Auto-reader Operator's Manual Troubleshooting Guide.
Retest the Auto-reader with a new positive control.
With processed 1492V BIs, a positive (+ on the display) result indicates a sterilization
process failure. A final negative processed 1492V BI reading (- on the display) after
the specified incubation time indicates an acceptable sterilization process.
Act immediately on any positive results for processed BIs. Determine the cause of
the positive BI following facility policies and procedures. Always retest the sterilizer
and do not use sterilizer for processing loads until three consecutive BI results
are negative.
Optional Visual pH Color Change Result
The 1492V BI is normally discarded after the fluorescent result has been recorded.
If, however, special studies are desired, 1492V BIs may be further incubated for
a visual pH color change result. After activation and during incubation, the white
Nonwoven Material will absorb the bromocresol purple indicator, the pH-sensitive
indicator dye in the growth media, and appear blue. In the case of the positive
control BI a yellow color change of the growth media and/or Nonwoven Material will
appear within 48 hours. Any observation of a yellow color within the vial indicates
a positive result.
In the case of a processed 1492V BI, a media and/or Nonwoven Material color
change from purple to yellow indicates a sterilization process failure. A negative pH
color change result, i.e., media and Nonwoven Material remain purple/blue, can be
assessed at 48 hours.
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